Generally, a way of thinking is known in which defects on a photomask are retouched. The necessity of the retouching increases as the photomask increases in area.
The way of thinking, in which the pattern on the photomask is retouched, is also applied to retouching of other pertinent fields, for example, a color filter or the like in a color liquid-crystal display panel. However, such techniques are common to each other in retouching of a pattern which is formed on one side of a substrate and which has partially defects.
For instance, Japanese Patent Unexamined Publication (Kokai) No. SHO 54-32978 discloses such a technique that, primarily in retouching of pattern defects of the photomask, a protective membrane or layer is formed at least on the pattern surface of the side of the substrate prior to illumination of a laser, and the illumination of the laser is done such a condition that the side of the substrate is protected, whereby portions of the protective layer are prevented from scattering and from adhering to the remaining portions of the protective layer so that the remaining portions form new defects. In addition, Japanese Patent Unexamined Publication (Kokai) No. SHO 62-191804 discloses such a technique that a laser having its wavelength equal to or less than 1 .mu.m is applied to remove foreign matters adhering to a color filter, together with construction substance of the color filter, which is located adjacent the foreign matters.
By the way, if the portions of the photomask or the color filter, from which the foreign matters are removed, are left as they are, the portions are brought to falling conditions and form different defects. To this end, it is necessary to fill the falling portions with pattern material or other retouching materials. In retouching of the color filter, particularly, consideration must be made to uniformize membrane thickness of the filled retouching material to the thickness of the past pattern or the original pattern.
In this respect, Japanese Patent Unexamined Publication (Kokai) No. SHO 61-122605 discloses such a method that, as a technique in which breaking portions of pigments of a color filter are retouched or restored, an entire side of a substrate including a pigment layer is first coated with a photoresist, portions of the pigment layer including the breaking portions of the pigments are then removed together with the photoresist, by illumination of a laser, to expose a portion of the substrate, a pigment layer is then formed on the substrate by vacuum-deposition and, subsequently, residual photoresist is dissolved and removed. According to this method, it is possible to form, by vacuum-deposition, the pigment layer for retouching under the same condition as the past pigment layer to be retouched, thereby bringing the thickness of the pigment layer of the retouched portions substantially to the thickness of the past pattern.
In such retouching technique of the color filter, however, the retouching of the breaking portions of the pigments must be done for each color, that is, the retouching must be done in numbers corresponding to the colors such that a first pattern is formed, the first pattern is subsequently retouched, a second pattern is then formed, the second pattern is subsequently retouched and so on.
The inventors of this application have considered various methods which have more easily conduct retouching of an article having a plurality of types of patterns such as the color filter.
As a result, the inventors has noticed a method in which, after the plurality of types of patterns have all been formed, these patterns are retouched at once. In this method in which the patterns are retouched at once, a procedure is taken in which retouching material is partially filled in a plurality of portions to be retouched and that pattern portions different in type from each other, depending upon a place.
FIG. 2 shows a condition under which a foreign matter or the like is removed, and retouching material 2 is coated on a portion to be retouched in which one side of a substrate 1 is exposed. The retouching material 2 fills a defect portion of a pattern 3, and a part of the retouching material 2 adheres to an inner periphery of a retouching protective membrane 4 and an upper surface thereof.
A material section 2a on the retouching protective membrane 4 can be removed by removing the protective membrane 4. However, it is difficult to remove a material section 2b at a portion on the inner periphery of the protective membrane 4. As a result, there is a fear or likelihood that the material section 2b at the inner peripheral portion of the protective membrane 4 is left in the form of a projection at a peripheral edge portion of a material section 2c which fills the defect portion, so that the projection forms a new defect. In this respect, in case where the retouching protective membrane 4 is formed thick, concretely or definitely, to a value equal to or thicker than 1.5 .mu.m, the thickness of the material section 2b remaining at the inner peripheral portion of the protective membrane 4 increases. Accordingly, when the pattern 3 is large in its thickness per se such as a color filter as compared with a case of a photomask, the above-described problem is more remarkable. Further, in case of the color filter, the projection mentioned above causes a display quality to be deteriorated so that its influence is large.